MXPA04003959A

MXPA04003959A - Method and apparatus for the production of metal powder.

Info

Publication number: MXPA04003959A
Application number: MXPA04003959A
Authority: MX
Inventors: Suzuki Kazuaki
Original assignee: Phild Co Ltd
Priority date: 2001-10-29
Filing date: 2002-10-24
Publication date: 2004-11-29
Also published as: BR0213735A; HUP0401662A2; US7300491B2; EP1449605A1; EP1449605A4; NO20042178L; CN1311898C; PL369221A1; WO2003037553A1; US20050092132A1; JPWO2003037553A1; CA2464910A1; KR20050039690A; CN1575215A; TW561085B

Abstract

A method for producing a metal powder which comprises effecting a plasma discharge in water between an electrode of an elemental metal and a counter electrode to generate a metal ion vapor and contacting the metal ion vapor with water to thereby convert the metal ion vapor to a powder; and an apparatus for producing a metal powder which comprises a power source for high voltage high current discharge, a device for supplying an electrode of a metal such as titanium, a high voltage discharge device having an electrode of a metal such as titanium and a counter electrode, a device for vibrating or sliding anelectrode, a water tank, a water inlet, an outlet and a discharge pump for discharging a dispersion of a metal such as titanium, and a device for separating and recovering a powder of a metal such as titanium. The method and the apparatus allows the production of a metal powder having high purity and being uniform in the shape and size of particles, at a low cost.

Description

METHOD AND APPARATUS FOR THE PRODUCTION OF METAL POWDER Field of the Invention The invention relates to a method and apparatus for producing, in an inexpensive manner, metal powder, which offers high purity of the elemental metal and which comprises powder particles of uniform size and configuration. The invention also relates to the production of the aforementioned metal powder of titanium, zirconium, germanium, tin, gold, platinum and silver, but is mainly applied to the production of titanium powder.

Background of the Invention Elementary metal materials, especially those that offer a high purity of elemental metal, are processed in various configurations and sizes, in accordance with the required applications, such as molded powder products, metal sheets, rods, wires thin and sheet materials. In recent years, metal powder, which offers high purity, has attracted attention as an effective molding material for use in various molding processes, such. such as powder metallurgy and thermal spraying. This powder metallurgy is an important technology used in fields that vary widely, which include the production of mechanical parts. Therefore, the demand for metal powder, as a material of powder metallurgy, is also growing. Traditional methods for producing metal powder include the classical method of crushing, mechanically and directly, powdered metal particles, and the method for blowing the molten metal using gas and configuring the blown droplets in powder form. However, these methods have problems, for example irregularities in the configuration and particle size, poor economy, etc. Electrolysis is one of the known, relatively new methods for producing metal powder. However, electrolysis has been reported to produce metal from a spongy and brittle powder structure, if the deposit of the metal is performed under a condition outside the optimum range, where the metal of a crystal structure, smooth, fine and uniform, can be to deposit. Even when the deposit is achieved under an optimal condition. the metal powder obtained by the method of electrolysis, as presently known, does not satisfy the required levels of purity or uniformity of the configuration and size of the metal particles. Other problems associated with these methods is that the poor economy also remains unsolved. Among other metals, titanium is a relatively new metal, compared to iron or copper, which has been known since ancient times, or aluminum. Being light in weight and offering excellent strength and resistance to corrosion, under high temperatures, titanium metal is used in a wide range of industrial applications. Examples include the material of a jet engine, structural elements and other parts used in airplanes and spacecraft, materials for heat exchangers used in thermal or nuclear generation, catalyst materials for use in polymer chemistry and articles of daily use, such as eyeglass frames and golf club heads. Titanium is also used by other fields, which include products for health, medical equipment and materials details, and applications of titanium are expected to increase further. Titanium is already competitive with stainless steel and duralumin, and will probably become a material that will have a higher demand than those rival metals. The titanium metal has poor processability and cutting property and, therefore, a dispersed titanium material is used in the production of mechanical parts that have a complex configuration and require additional machining steps, such as cutting, after forging hot, laminate or other plastic process of work. This inevitably increases the stages of the process and adds to the production costs. For the above reasons, powder metallurgy is often used in applications in which titanium metal is used, as mentioned above, and, therefore, there is a demand for a titanium powder that offers high purity and particle size and configuration uniforms When the titanium powder is produced, using conventional powder production methods, applicable to general metals, the titanium powder produced will have problems, just like other metals produced in the same way, in terms of irregularities in the configuration and size of the titanium powder. particles, poor economy, etc. Therefore, a method for producing the titanium powder, which can provide high purity and a more uniform particle size and configuration, is long expected. For example, improved production methods of the titanium metal powder, which uses the hydrogenation and dehydrogenation method and the rotary electrode method, are already in commercial use. The hydrogenation and dehydrogenation method is a technique for heating the dispersed titanium material, the titanium sponge, or titanium waste generated from the cutting / machining processes, in a hydrogen atmosphere, to cause the titanium material to absorb the hydrogen gas, and then the brittle titanium material is ground, after which the crushed titanium is again heated in a vacuum atmosphere to release the hydrogen gas and consequently obtain the titanium powder. The rotary electrode method uses a round bar, formed of the dispersed titanium material or the dispersed, processed titanium material, which is a forged, laminated or otherwise processed version of the dispersed titanium material. This round bar material is rotated at high speeds in an atmosphere of inactive gas, such as argon or helium, while its tip is dispersed using a heat source, such as a bow or plasma arc, and molten metal dripping is spread by centrifugal force to obtain spherical particles of dust. In the rotary electrode method, controlling the dispersion amount of the dispersion metal is very difficult. The titanium powder obtained by the hydrogenation and dehydrogenation method has an irregular sphericity. Therefore, although such powder can be used for die casting, the heating process must be repeated twice. While the mechanical crushing process using a ball mill can be devised, it would inevitably cause oxygen contamination of the titanium powder. On the other hand, the rotary electrode method, in which the molten titanium material is formed as a powder in an atmosphere of an inactive gas, produces spherical powder particles with good fluidity and there is no risk of oxygen contamination. However, this method has the drawback of poor solidification of the molding material. In addition, both methods use the process in batches and, therefore, the costs of dust production are greater. The atomization method was developed as a method of production of titanium powder, which is aimed at solving the aforementioned problems related to quality and production costs. Under the atomization method, the metal material is dispersed in a copper crucible, cooled with water, using a plasma arc or other source of heat, and the molten metal is dripped from either end of the crucible. Then, an inactive gas, such as argon helium, is injected into these drops of molten metal, to atomize the molten metal and obtain the powder, however, this method could not achieve significantly lower production costs compared with conventional methods. , since it also uses the dispersed titanium material and the processed dispersed titanium material. The invention described in Japanese Patent Application, Open to the Public, No. 5-93213, a method for producing titanium powder, which offers improved sphericity and fluidity to facilitate molding, in a way that requires lower production costs and avoids contamination with oxygen. However, this method, in which the titanium sponge is pressed isostatically in the cold state and the solidified stick material is melted in an inactive gas atmosphere and then an inactive gas, such as argon or helium, is injected to atomize the molten metal to obtain a powder, still does not supply the powder of the desired purity levels, as well as the uniform sphericity and particle size, the production costs are not ideal either.

Exposure of the Invention Despite the needs and demands of growth for metal powder - especially titanium metal powder - as mentioned before, at the bottom of the advance in the new methods of molding / process, such as metallurgy In powder form, the powder production methods developed so far have not been able to completely solve the requirements for the production of such metal powder. In particular, these methods have problems in the purity of the elemental metal, the uniformity of the sphericity and the particle size and the production costs. In view of the above situation, the present invention is directed to produce and provide powdered material that offers excellent uniformity of sphericity and particle size and high purity of the elemental metal, for use in molding processes, such as powder metallurgy. After studying numerous ways to improve the problems associated with the production of the elemental metal powder, such as titanium powder, include the poor purity of the elemental metal, irregularity of sphericity and particle size and high production costs, the inventors have Successfully solved the aforementioned problems, using the technology presented before by the inventors, relating to the production of high function water containing titanium (Japanese Patent Application No. 2001-315446). The above-mentioned invention relates to the production of titanium-containing high-performance water (Japanese Patent Application No. 200-315446) refers to a method for producing high-function water, in which the titanium metal is micro- dispersed by causing a plasma discharge into the water, between a titanium metal electrode and its counter-electrode, and then causing the vapor of metal ions generated to make contact and disperse in the water. The present invention uses this technology to enable the production of elemental metal powder, especially titanium metal powder, which offers excellent purity and uniformity of sphericity and particle size, with a significantly lower production cost. The method and apparatus proposed by the present invention are fundamentally different in concept and structure from conventional production methods for metal powder and titanium powder. Basically, the present invention is directed to obtaining metal powder as sediments in the water, causing the discharge of plasma into the water and thus converting the elemental titanium metal into fine particles. This technique can also be applied to other metals besides titanium, and the production method and apparatus proposed by the present invention actually incorporates a remarkable improvement in the production of the metal powder, based on a different approach completely from those adopted by the conventional methods. Specifically, the present invention, in which the basic concept is to cause the discharge of the plasma in water, between the elemental metal electrode and its counter-electrode, and then cause the ion-generated metal vapor to make contact with the water and arrive to be a powder form, comprising steps (1) to (7) specified below: (1) A method for producing metal powder, in which the plasma discharge is caused within the water, between an electrode made of the elemental metal and its counter electrode, and the vapor of metal ions generated is brought into contact with the water and become a form of dust. (2) A method for producing metal powder, as described in (1) above, in which the elemental metal is titanium, zirconium, germanium, tin, gold, platinum or silver. (3) An apparatus for producing metal powder, which comprises supplying the high voltage / current discharge, an elemental metal electrode feeder, a high voltage discharge generator, equipped with an elementary metal electrode and its counterpart. electrode, a water tank, a water inlet to said water tank, an outlet for the dispersion water produced, fine particles of elemental metal, a discharge pump and a filter system. (4) The apparatus for producing the metal powder, as described in (3) above, in which titanium, zirconium, germanium, tin, gold, platinum or silver is used as the elemental metal. (5) The apparatus for producing metal powder, as described in (3) or (4) above, in which the elemental metal, which constitutes the electrode, has a bar, plate or wire configuration. (6) The apparatus for producing the metal powder, as described in any of (3) to (5) above, in which an elemental metal electrode is made and its counter-electrode made of carbon, and a pair of Electrodes are vibrated or slid to prevent fusion between the electrodes, and where the instantaneous plasma discharge is generated to control the amount of dispersion. (7) The apparatus for producing metal powder, as described in any of (1) to (6) above, in which the amount of the current flowing through the circuit can be adjusted easily, changing the diameter and / or length of the carbon electrode.

The method and apparatus proposed by the present invention allow the production of elemental metal powder in a very efficient manner. In addition, the present invention does not generate by-products or impurities, in addition to the target metal powder. The generation of the metal oxide due to the heating of the metal material is also very small, the particles of the metal powder obtained have an excellent uniformity in their sphericity and size and the production costs can be significantly decreased. Continuous production is also possible, in addition to batch production, so that metal powder of uniform particle size can be produced in bulk volumes in an economy that sufficiently meets the requirements for such commercial production. In the production process, proposed by the present invention, plasma discharge is caused in water, between the elemental metal electrode and its counter electrode, to obtain ion vapor from the elemental metal. As the vapor makes contact with water, it instantly disperses in water like fine particles, to become a fine powder. In addition, because the counter-electrode used in such plasma discharge under water, the same metal is not formed as the elemental metal electrode, but carbon, and also by the vibration and slippage of the electrode pair, the Fusion between the electrodes can be prevented. Also, the achievement of instant plasma discharge makes it easy to control the amount of dispersion and there is no need to select a different power supply for a given purpose, because the amount of current flowing through the circuit can easily be adjusted , changing the diameter and length of the counter-electrode, made of carbon. The carbon particles that disperse simultaneously with the metal particles are less harmful and almost all of their amount can be easily removed using a filter system, thus enabling a high purity metal dispersion water production. Through these processes, the fine particles of the elemental metal used as an electrode are obtained as proposed by the present invention. According to the present invention, the fine metal powder of zirconium, germanium, tin, gold, platinum or tin can be produced in addition to the titanium powder, using a suitable metal as the material of the elemental metal. The basic structure of the present invention provides a method for producing metal powder of a uniform particle size, causing discharge of the plasma into water, between an electrode made of elemental metal, and its counter-electrode made of carbon, etc. , and then causing the ion vapor of the generated metal to come into contact with the water and thus arrive at a powder form, as explained above. The production flow diagram, shown in Figure 1, delineates this production process.

As shown in Figure 1, distilled water or other demineralized water is filled into a water tank, used for the production of titanium metal powder. Then, an electrode, made of titanium metal, in the form of a rod, etc., is fed to a feeder of the electrode of the elemental metal, and the discharge of the plasma in the water between the electrode of the elemental metal and its counter electrode is caused. , made of a carbon bar. When the ion vapor of the elemental metal, generated by the discharge under water, makes contact with this water, the vapor will instantly disperse in the water. At this time, titanium particles of very fine size, of micrometer scale, are produced and dispersed as a powder, to form the dispersion water of the elemental metal. This very fine elemental metal powder in the water does not melt or float and instead settles after a short period. This powder can be refined by filtering to obtain the elemental metal powder. This fine elemental metal powder obtained has high purity, as well as a uniform sphericity and particle size.

Brief Explanation of the Drawings "Figure 1": a diagram of the production flow of the metal powder, as proposed by the present invention. "Figure 2" is an apparatus for producing metal powder, as proposed by the present invention.

Explanation of Symbols 1. Generator of plasma discharge 2. Power supply for high voltage discharge / current 3 Electrode vibration / slip device. 4 Elemental metal electrode feeder 6. Elemental metal electrode 7. Contra-electrode 8. Water inlet. 9. Outlet for elemental metal dispersion solution 10. Discharge pump 11. Filter system 12. Filtering 13. Metal pole 14 Water tank.

The Best Way to Carry Out the Invention An example of the production of titanium metal powder is explained below. Note, however, that the present invention is not limited to the production of titanium powder. Although the present invention allows the production of the pure titanium powder, in a very efficient manner, the control of the charging regime of the electrode, made of the titanium metal, is very important in achieving such efficient production of the pure titanium powder. For example, the amount of current flowing through the circuit can be adjusted by changing the diameter and length of the carbon counter-electrode, as one of these resources. According to the production apparatus proposed by the present invention, the discharge of the plasma is caused in the water within a water tank. Therefore, it is necessary that the water tank has a sufficient resistance to pressure, which can withstand the high pressure required in the discharge of the plasma under water. In addition, because the counter-electrode used in the discharge, is not the same metal as the electrode of the elemental metal, but carbon, and also by the vibration and displacement of the pair of electrodes, the fusion between the electrodes can be prevent. Also, the achievement of instant plasma discharge makes it easy to control the amount of dispersion and there is no need to select a different power supply for a given purpose, because the amount of current flowing through the circuit can be easily adjusted changing the diameter and length of the counter-electrode cylinder, made of carbon. The particles of carbon that are dispersed simultaneously in the metal particles of the element, are less harmful and almost the entire amount of them can be easily removed by means of filtration, thus enabling a dispersion water production of high elemental metal. purity. The electrode made of the titanium metal material may have a bar, plate or wire configuration. In the case of a small production tank, with a much smaller capacity of one ton, it will be more appropriate to introduce the titanium metal as a wire, instead of a bar. Other materials of elemental metals, in addition to titanium, from which the metal powder can be produced, using the production apparatus proposed by the present invention, include zirconium, germanium, tin, gold, platinum and silver. However, possible applications of the present invention are not limited to these elementary metals mentioned. An example of the present invention is explained in accordance with the drawings. Note, however, that the present invention is not limited to this example. Figure 1 shows a diagram of the production flow of a metal powder, according to the present invention, as explained above. Figure 2 illustrates an apparatus for producing the metal powder proposed by the present invention, which comprises a water tank (14), a plasma discharge generator (1), equipped with an electrode of an elementary metal, and its anti-electrode, and a filter system (11), to filter the elemental metal powder. A container, resistant to pressure, used for the production of the metal powder, is equipped with a power supply for discharge (2) of high voltage / current, a device for vibrating or sliding the electrodes (3), a device for feeding the electrode (3) of the elementary metal, the plasma discharge generator (1) is equipped with an electrode (6) of the elemental metal and its counter-electrode (7), an inlet 88) of water to the water tank (14), an outlet (9) ) of the dispersion solution of the elemental metal, generated by the discharge of the plasma into water, a discharge pump (10) for the filter system (11) to separate the metal powder from the dispersion solution of the elemental metal. The powder produced is denoted as (13). The demineralized water is fed into the water tank, which is installed in the plasma discharge generator. This plasma discharge is caused between the electrode of the elemental metal of titanium and its counter-electrode, made of carbon, which are both submerged in the water inside the tank. The discharge of the plasma under water generates titanium ion vapor, and when this vapor makes contact with the water, a dispersion solution of the titanium metal is produced. For the discharge of the plasma, the fusion between the electrodes can be prevented by the vibration or sliding of the electrodes, using a device (3) of sliding 7 vibration, and the achievement of the instantaneous plasma discharge makes it easy to control the amount of dispersion . In addition, the electrode of the titanium metal is fed continuously or intermittently, using the feeder (4) of the electrode, to ensure that the electrode is consumed in sequence by the necessary amount. The plasma discharge underwater instantly melts the titanium material and thus causes the molten titanium to disperse in water. In this process, fine, very small titanium particles of micrometric scale (4) are generated and dispersed as dust. The generated titanium metal powder does not melt or float and instead settles like a pole, after a short period, to separate from the water. The water obtained is recovered from the powder (9) exit of titanium metal and filtered through the filter system (1) in the filtrate (12) and the powder (13) of titanium. When 25 kg of the titanium metal bar is consumed in a water tank filled with one ton of water, the resulting water contains a small amount of dissolved titanium. However, the rest of the titanium electrode sediments at the bottom of the container as titanium powder. The average particle size of this titanium powder is 10 to 30 μp ?. In addition, the titanium powder obtained does not contain by-products or impurities and the particles of the titanium powder have a very uniform sphericity and particle size.

The present method and apparatus truly produces titanium powder of uniform particle size, in a very economical manner.

Industrial Field of Application The present invention allows the production in a very efficient and stable manner of the metal powder, especially the titanium powder, which offers high purity. The production method, proposed by the present invention, eliminates the generation of by-products and impurities, in addition to the content of the target metal, and the obtained powder has an excellent uniformity in terms of sphericity and particle size. Additionally, the compact, efficient device achieves a significant reduction in production costs. Also, the present invention can be applied to intermittent production, continuous production and mass production.

Claims

2. 3 CLAIMS

1. A method for producing metal powder, this method comprises: causing the discharge of the plasma in a high pressure water, between an electrode made of the elemental metal and its counter-electrode, to generate metal ion vapor; and contacting the ion value of metal generated with water, to convert this metal ion vapor into metal powder.

2. The method for producing metal powder, as described in claim 1, wherein the elemental metal is titanium, zirconium, germanium, tin, gold, platinum or silver.

3. An apparatus for producing metal powder, this apparatus comprises: a power supply, for the discharge of high voltage / current; a feeder, to supply an elementary metal electrode; a high voltage discharge generator, equipped with an electrode, made of elemental metal, and its counter electrode; a water tank; 24 a water inlet to this water tank; an outlet for the dispersion water produced, from fine particles of the elemental metal to a discharge pump; and a filter system.

4. The apparatus for producing a metal powder, as described in claim 3, wherein the elemental metal is titanium, zirconium, germanium, tin, gold, platinum or silver.

5. The apparatus for producing a metal powder, as described in claim 3 or, wherein the elemental metal constituting the electrode has a bar, plate or wire configuration.

6. The apparatus for producing a metal powder, as described in any of claims 3 to 5, in which the counter-electrode is made of carbon, and an apparatus for vibrating or sliding the electrodes is provided between said power source and said electrodes to prevent fusion between the electrodes, and where the instantaneous plasma discharge is generated for control the amount of dispersion. The apparatus for producing a metal powder, as described in claim 6, wherein the amount of current flowing through the circuit is adjusted by changing the diameter and / or length of the counter-electrode, made of carbon. 8. A method for producing a metal powder comprising: causing the discharge of plasma into water between an electrode made of elemental metal and its counter-electrode, to generate metal ion vapor; and contacting the metallic ion vapor generated with water to convert the metal ion vapor into metallic powder.